On July 6 1988, a serious incident occurred that is still sending shockwaves through medical, administrative and political circles. Although the conclusions from the saga are still, 18 years on, not yet complete, it is a microcosm of how badly public authorities can react when confronted with something that has gone seriously wrong. It offers a textbook example of lessons that need to be learned if trust is to be regained in public life.

That date in 1988 was the day of the Camelford acid water incident in Cornwall. Twenty tonnes of aluminium sulphate was accidentally dumped into the wrong tank at Lowermoor water treatment works on the edge of Bodmin Moor. For five days people were told the water was safe to drink, but that it should be boiled - unfortunate advice, because boiling concentrated the contaminants.

Immediate symptoms included nausea and vomiting, skin rashes and mouth ulcers. Others noted that their hair, skin or finger nails had been stained blue or brown. No medical help was offered until local residents formed a collective. They were told that because the incident was chemical not bacteriological, it was deemed wholly a matter for the water company. But the medical officer of the water company admitted he had no expertise in biochemistry.

The following month, an official from the Department of Health (DoH), Michael Waring, wrote to every doctor in Cornwall saying that, although he had no detailed information on what exactly was in the water or how much people might have drunk, he could assure them that no lasting ill effects would result.

Meanwhile, local Conservative MP Gerard Neal had assured his constituents that he would seek a public inquiry. A few weeks later, he changed his mind and told people they were not suffering real ill health but psychosomatic symptoms led by the hysterical behaviour of the media. A year later, he was congratulated in parliament by the then health secretary, who sympathised with him because of the "troublemakers" he had had to deal with. It may be relevant that, at this time, the Tory government was gearing up for water privatisation.

Also in August, Elizabeth Sigmund, a member of the local residents' collective, contacted a senior toxicologist at the DoH, GK Matthews, to seek help and advice. He suggested a team of medical experts should at once be sent to North Cornwall. A month later, he said he had attended meeting after meeting in the department at which he "was overruled".

Public concern, however, did not abate, and in January 1989 the government was forced to appoint a team of scientists to investigate. Dame Barbara Clayton, famous for her report on whether lead in car exhaust fumes could damage children's health, was chosen as head.

The team flew to Camelford and interviewed several people who had suffered ill health. It then held a press conference to give its view that the symptoms being experienced could not be related to water. This report still did not allay public anxieties and Clayton was asked to write a second. She concluded again that her first conclusion was correct.

Surprising result

Meanwhile, in the summer of 1989, patients started to lose toe and finger nails, and John Eastwood, a renal consultant at St George's hospital, Tooting, south London, was asked, as an independent initiative, to arrange two bone biopsies on patients from North Cornwall. These showed a discrete layer of aluminium in the deep bone - a surprising result that could not have resulted from normal aluminium absorption. No official action was taken to follow up the implications of this, and there the matter lay for a decade.

In 2000, I was asked as environment minister by the Liberal MP, Paul Tyler, to visit Camelford to witness for myself the widespread public distress still being caused to the local population by the absence of any detailed examination of their symptoms. After listening for a day to the evidence presented, I was persuaded (contrary to my briefing) that a much fuller investigation was needed. The Lowermoor sub-group study was set up, and it reported in 2005.

However, internal machinations continued. The requirement to examine the DoH's handling of the incident was removed from the terms of reference. No independent expert on aluminium toxicology was included in the working group. An attempt was made to include Waring as medical adviser to the group, even though he was the author of the original letter stating that no lasting ill effects would result.

Furthermore, no objective testing of the exposed population was carried out. Too much reliance was placed on the water sample analysis from the South-West Water Authority, the compromised party. The amount of sludge reported to have been in the contact tank at the time was ignored, even though it was critical in estimating whether the concentrations people were exposed to were much higher than might otherwise have been expected. And experts were drawn on who had potentially vested interests in the aluminium industry.

Despite these flaws, the DoH, which appointed the chairman and secretary to the group, pre-released a highly misleading statement of the findings two days before the draft report was due to be made public. This, and the equally misleading and biased executive summary prepared by the secretariat without the group's approval, effectively concluded that the illnesses reported bore no connection with the water poisoning.

But the story does not end there. The wife of one of the members of the study group died of what a pathologist described as "a very unusual pattern of severe sporadic amyloid angiopathy", with extremely elevated levels of aluminium deposition in the most severely affected areas of the brain. In addition, a 45-year-old woman who had also been exposed to the most highly contaminated water in 1988 took her own life after developing delusions and similar medical symptoms.

It has also just come to light that the police in 1989 assembled 7,000 pages of documentary evidence, reviewed by JW Bridges, professor of toxicology at the University of Surrey, for the prosecution of South-West Water Authority. But this medical evidence was never used.

This is a tragic story - at best of obfuscation and bureaucratic inertia, at worst of downright official hostility and obstruction. One can only surmise what political, administrative or industrial motives have been behind it.

But what is clear is that there needs to be a radical overhaul of the system of redress if there is to be the openness, transparency and justice that people in Britain today should have a right to expect.